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,. nf" !!!'J . v iJ_ i)", . , & C Affected t=nvlfonment onsequences Table 3-9. Gunnison River below Gunnison Tunnel (cfs) Alternative Month A E-l E-2 E-3 Jan 1352 594 650 713 Feb 1330 626 676 735 Mar 1240 638 685 743 Apr 1017 729 761 794 May 1262 1088 1088 1110 Jun 1569 1343 1344 1361 Jul 1443 1327 1329 1335 Aug 784 752 752 752 Sep 626 481 495 488 Oct 768 443 460 482 Nov 1107 485 542 601 Dee 1302 581 655 730 Annual 1149 756 784 818 Reclamation is currently considering changing the operating plan for the Aspinall Units to discharge water from the reservoirs to create a more natural hydrograph in the river in its downstream reaches, and has been testing various operating schemes during the past several years. These test flows have been designed to study endangered fish habitat. These years are included in the Sponsors' hydrologic model. The "with Project" flows entering the Black Canyon are shown in Tables B-1 through B-4 in Appendix B of this SEIR. In these tables, the effects of the test flow changes in Aspinall operations can be seen by comparing the years 1991 through 1996 to earlier years in the period of study. Recommendations will be received from the FWS on Aspinall Unit operations in 2000. It is anticipated that the recommendations will call for higher spring flows with lower flows during other periods. In general, the proposed Aspinall operations' change would affect the Gunnison River between the Tunnel and Delta. The changes would reduce the amount of water passing the Gunnison Tunnel and entering the Black Canyon during the winter months, while increasing the flows during the spring and summer months. There would be no change in Gunnison River flows downstream from Delta. The Sponsors would operate the proposed Project as a run-of-the-river plant, and would accept and divert Gunnison River water only as it is available. Changing the Aspinall Unit operations are expected to diminish the supplies available to the proposed Project. The Sponsors have indicated that they are willing to accept this risk. AS Lateral Hydropower Project July 2000 3-9